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Reachable AssertionWeakness · CWE-617

CVE-2026-14586

MEDIUM · 5.9 CVSS v3.1 Developing Published 2026-07-22
No fix yet
No fix has been published. The vendor has not shipped a fixed release or patch. You remain exposed.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click 4 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In NLnet Labs Unbound 1.22.0 up to and including 1.25.1, in DNS-over-QUIC environments, with high concurrency and under pressure, an assertion in libngtcp2 about monotonic timestamps could trigger and result in server termination and thus denial of service. When interfacing with libngtcp2, for DNS-over-QUIC support in Unbound, it is expected to use monotonic time. Unbound was using realtime instead, and in DoQ environments with high concurrency and under pressure, an assert in libngtcp2 for the quic timestamp would trigger and terminate the server.This vulnerability needs Unbound to be compiled with DoQ support ('--with-libngtcp2') and the 'quic-port' to be configured for the listening interfaces.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-08-05.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Recommended fix High confidence

Unbound 1.25.2 or later (any version after 1.25.1)

  1. 1. Identify the current Unbound version by running 'unbound -V' or checking the package manager
  2. 2. Verify if Unbound was compiled with DoQ support (--with-libngtcp2) and has 'quic-port' configured by reviewing the configuration file (typically unbound.conf)
  3. 3. If DoQ is in use, plan for the upgrade to version 1.25.2 or later
  4. 4. Download the fixed version from the official NLnet Labs Unbound download page: https://www.nlnetlabs.nl/downloads/unbound/
  5. 5. Before upgrading in production, test the new version in a staging environment to verify DoQ functionality works correctly
  6. 6. Apply the upgrade using your system's package manager or compile from source with the same configuration options previously used
  7. 7. After upgrade, verify the server starts successfully and monitor for any assertion failures related to quic timestamps
Caveat Minimal risk - this is a bug fix. However, as with any upgrade, test DoQ functionality in a non-production environment first to ensure compatibility with your specific configuration.

Generated from the published advisory — verify against the referenced sources before acting.

No vendor fix exists The vendor has not published a patch for this.

There is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-14586 in production — separate from our analysis above.

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